#include <bits/stdc++.h>
using namespace std;

using VI = vector<int>;
using VVI = vector<VI>;
using PII = pair<int, int>;
using LL = long long;
using VL = vector<LL>;
using VVL = vector<VL>;
using PLL = pair<LL, LL>;
using VS = vector<string>;

#define ALL(a)  begin((a)),end((a))
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define SZ(a) int((a).size())
#define SORT(c) sort(ALL((c)))
#define RSORT(c) sort(RALL((c)))
#define UNIQ(c) (c).erase(unique(ALL((c))), end((c)))

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

#define FF first
#define SS second
template<class S, class T>
istream& operator>>(istream& is, pair<S,T>& p){
  return is >> p.FF >> p.SS;
}
template<class S, class T>
ostream& operator<<(ostream& os, const pair<S,T>& p){
  return os << p.FF << " " << p.SS;
}
template<class T>
void maxi(T& x, T y){
  if(x < y) x = y;
}
template<class T>
void mini(T& x, T y){
  if(x > y) x = y;
}


const double EPS = 1e-10;
const double PI  = acos(-1.0);
const LL MOD = 1e9+7;

int main(){
  cin.tie(0);
  ios_base::sync_with_stdio(false);

  int N, M;
  cin >> N >> M;
  VVI G(N);
  REP(i,M){
	int a, b;
	cin >> a >> b;
	G[a].PB(b);
	G[b].PB(a);
  }

  vector<bool> vis(N);
  function<void(int)> dfs = [&](int u){
	if(vis[u]) return;
	vis[u] = true;
	for(int to: G[u])
	  dfs(to);
  };
  REP(i,N){
	if(!G[i].empty()){
	  dfs(i);
	  break;
	}
  }

  bool ng = false;
  REP(i,N)
	if(!G[i].empty() && !vis[i])
	  ng = true;

  int odd = 0;
  REP(i,N) odd += SZ(G[i]) % 2;

  if(ng || odd > 2)
	cout << "NO" << endl;
  else
	cout << "YES" << endl;

  return 0;
}